Dachs, App, and Dlish form a core complex to promote growth. (A) Ectopic Dachs expression causes increased App abundance. (B) Conversely, ectopic App expression does not increase Dachs abundance but does result in a more punctate appearance at the junctional cortex. (C) Comparison of apical protein levels of Dachs, Dlish, and App in response to ectopic expression of other core complex components. Y axis shows the mean intensity ratio of the posterior compartment (ectopic expression) to the anterior compartment (normal cells). ****P < 0.0001, ** 0.001 < P < 0.01, * 0.01 < P < 0.05 (two-tailed unpaired t test between each genotype). App:YFP in wild-type (n = 28), hh>dachs (n = 20), and hh>dlish (n = 16); Dachs:GFP in wild-type (n = 11), hh>dlish (n = 19), hh>app (n = 26); and anti-Dlish staining in wild-type (n = 12), hh>dachs (n = 15), and hh>app(n = 12). (D–K) Analysis of core complex components at the cell cortex in the absence of Ds and Ft. (D) Dachs and Dlish levels are highly elevated at the junctional cortex in ds ft mutant cells. (E) App:YFP abundance also is increased at junctions together with Dachs in ds ft clones. (F) In marked contrast to ds ft mutant cells (D″), Dlish is strongly reduced in ds ft dachs mutant cells. (G) App:YFP is less punctate but is junctionally localized in ds ft dachs mutant cells. (H) In the absence of dlish, Dachs abundance and localization are unaffected by loss of ds and ft. (I and J) In contrast, loss of ds and ft still causes increased Dachs and Dlish abundance at the junctional cortex in the absence of app (I), although the effect is smaller than when App is present (J). (K) Mutation in App catalytic domain has a similar effect on Dachs and Dlish accumulation as app null alleles (compare J and K). (L) Dachs:GFP localized to cell contacts also recruits App and Dlish in S2 cells (yellow arrows). Scale bars, 5 µm.